Tank cleaning machines are designed to operate under various environments and conditions. Some tank cleaning machines are quite complicated and use impeller-driven gear drives to rotate the spray nozzles over a variety of paths to create complicated spray patterns. For example, see U.S. Pat. No. 4,664,720. Other cleaning situations do not require such complicated and costly tank cleaning machines. For example, U.S. Pat. No. 5,316,218 shows a spray head having a nozzle body mounted to the end of a mounting member. The nozzle body has a generally spherical shape with a pair of slots through which the cleaning liquid is dispensed. The orientation of the slots causes the nozzle body to rotate around the outer end of the mounting member to provide a desired spray pattern.